The Science of Fluorescent Lighting

How does a fluorescent lamp work?

The origin of the fluorescent tube dates back to 1938, when it became
possible to produce radiation of visible wavelengths by exposing various
phosphors to ultraviolet radiation.

The source of this UV was a glass tube with electrodes on each end
and sealed. A small quantity of mercury is placed inside the tube along
with inert gases. With the glass tube in a state of low vacuum pressure,
the mercury vaporizes and acts as the conductor between both cathodes,
creating a mercury vapor arc resulting in the release of UV radiation
of 253.7 nanometres.

When a lamp of this design is produced with no phosphor coating, it
produces a very small amount of violet light and is considered to be
an ultraviolet lamp used for germicidal and sterilization purposes. It
is harmful for humans to be exposed to this type of lamp. Another variation
of this process is the tanning lamp, which is coated by phosphors that
allow a high percentage of the UV produced to radiate through. These
lamps are harmful if a person is exposed to them for more than the FDA
has allowed.

It is important to note that the operation of a standard 40 watt lamp
results in 60% of the energy being converted to UV radiation or approximately
24 watts. However, only 21% of this energy or 8.5 watts is transformed
into light. The remaining 39% of the UV energy and a total of 77% of
the total energy used by the lamp is transformed into heat, infrared
and radiated energy. Only 23% of the total lamp wattage is actually transformed
into visible spectrum or light.

Tube Diameters

What is a ballast?

A ballast is required for use with gas discharge lamps such a fluorescent,
to provide them with the necessary starting and operating electrical
conditions. Once the arc has been struck and the fluorescent lamp is
lit up, electrical resistance becomes negligible and the principal function
of the ballast is to limit current to the lamp while it is operating.

All PROMOLUX fluorescent tubes are designed to function
with industry standard ballasts. A ballast will have a label indicating
the wiring configuration and lamp types that should be used with it.
It is advisable to replace the ballast each time the lamp is replaced.

The Electronic Ballast and associated T8 fluorescent lamps have been
legislated as the new standard in North America. This is due to national
energy concerns, as well as concern for the environment. It is estimated
that 2 million fluorescent tubes are thrown in the trash each day.
The smaller diameter T8 lamps represent much less material such as
glass, mercury, metal, etc.

Electronic Ballast

Electronic ballasts substitute solid state circuitry for some of the
magnetic components used in conventional ballasts. An electronic ballast
operates
compatible
fluourescent lamps at a higher frequency then the 60 hertz (available
from utility) to improve performance and efficiency.